This invention relates to an apparatus for cleaning slices of material. More particularly, the invention relates to an apparatus for simultaneously cleaning both sides of a semiconductor wafer.
In the field of semiconductor manufacturing, it is necessary at certain stages to clean the semiconductor material. Thus, thin slices, generally referred to as wafers, of semiconductor material which have been cut from bulk material often have residual particulate matter and lubricants on their surfaces which must be removed prior to polishing. Furthermore, after polishing, and at other intervals in the process of making devices from the wafers, it is often necessary to carry out a cleaning operation. Since these wafers are quite thin, generally of 10 to 20 thousandths of an inch, and are quite brittle, their fragility presents a problem in designing suitable cleaning apparatus.
Various apparatus for cleaning semiconductor wafers have been disclosed in the prior art. For example, U.S. Pat. No. 3,585,668, describes an apparatus which holds the wafers on a flat surface and cleans one side of the wafers at a time. However, since it is often desired to clean both sides of the wafer, such an apparatus requires two separate steps for cleaning each wafer.
One solution to the problem of cleaning both sides of a semiconductor wafer is disclosed in U.S. Pat. No. 3,748,677 which describes an apparatus having a special disk which rotates vertically in a bath. A disadvantage of such a unit is that the wafers fall out after cleaning into a "cushioning bath" and then into a slice container, and the apparatus must be stopped in order to remove wafers therefrom. Furthermore, the removal step requires handling of the wafers which is a recognized disadvantage in wafer processing.